Here at InvestorPlace.com, our mission is to help investors make decisions on what stocks to buy, sell or, in some cases, even short.

But some companies are almost impossible to make a call on. And when that’s the case, sometimes the best call is no call at all.

After all, bad decisions can have severe consequences. If you’re wrong and sell a rising stock too early, you could lose out on making more money. Worse, if you’re wrong and SHORT a rising stock, you risk losing a lot of money. Naturally, you don’t want to get caught in a constant state of paralysis, but sometimes the best decision is the one you take a little more time to make.

So what are some stocks that fit in this indecision-for-now category? Here’s a look at three worth waiting on:

LinkedIn

LinkedIn (NYSE:LNKD) is the first name in professional social networking, and is in fact replacing the traditional concept of the paper resume.

With a user base of 174 million, LinkedIn is in an enviable position. It has three sources of revenues — Hiring Solutions, Marketing and Premium Memberships — which all are growing at a breakneck pace. The latest quarter’s revenues grew a sizzling 89%!

Despite all this good news, short sellers will reasonably point out that LinkedIn’s valuation remains at nosebleed levels of close to 1,000 times earnings! That’s thanks to a strong stock performance that has LNKD shares up 160% from their pricing and up 25% since the first-day pop. Plus, LinkedIn faces rising competition from fast-growing startups like BranchOut, and Facebook‘s (NASDAQ:FB) jobs board, while not an immediate threat, could eventually be an issue.

But so long as LinkedIn continues to grow, the valuation will probably remain robust. What’s more, the company has a knack for beating earnings estimates, which can spike the stock price. On the flip side, when a momentum stock loses steam — like Netflix (NASDAQ:NFLX) and Green Mountain Coffee Roasters (NASDAQ:GMCR) — the declines can be substantial.

Right now, the bear case probably outdoes the bull case for LNKD, but timing is the tough part. Investors need to keep their ears tuned into LinkedIn’s earnings front, and wait for news on that end before making a trade.

Under Armour

Under Armour (NYSE:UA) has built a tremendous brand that represents quality and innovation — and allowed the company to sell its wares at premium prices. Under Armour also has been aggressive with entering new categories, such as shoes, women’s clothes and even underwear, so the company remains committed to pursuing its high-growth strategy.

Of course, the company’s lofty price-to-earnings ratio of 63 screams of expectations for growth, too. The number is especially high in the sporting apparel space, where rival Nike (NYSE:NKE) sits at a multiple of 21.

Short sellers seem to believe that Under Armour’s valuation is vulnerable to a pullback, especially as rivals like Nike and Adidas (PINK:ADDYY) fight back. The current short interest is a 22.5%; a level above 10% is usually a sign of danger.

Under Armour looks like a toss-up right now. If growth decelerates, the stock is likely to plunge. Then again, it has a large market opportunity and a strong product line, which could mean continued gains. Unless a move brings that P/E down, or something indicates a tidal shift in the company’s business growth, you’re better off keeping your finger off the trigger.

Amazon.com

Amazon‘s (NASDAQ:AMZN) valuation always has been controversial. No matter what setbacks Amazon has faced, the stock keeps rising, and it does so at sky-high P/Es. AMZN shares currently trade at more than 300 times earnings — to put that in perspective, Facebook (NASDAQ:FB) trades at “just” 64 times earnings and Google’s (NASDAQ:GOOG) P/E is a threadbare 21.

And investors just don’t care. They firmly believe that Amazon is disrupting the massive retail marketplace, eating away at companies like Best Buy (NYSE:BBY), Costco (NASDAQ:COST) and Wal-Mart (NYSE:WMT). It doesn’t hurt that Jeff Bezos has tremendous credibility on Wall Street and has an innate understanding of finding growth.

The mantra at Amazon.com is to focus on low prices — for everything. Just look at last week’s launch of its new Kindle tablets. Even with top-notch features, they are still priced at rock-bottom levels. But that low-cost gamble has resulted in Amazon experiencing volatility in its results. In February, the company posted weak quarterly earnings and the stock fell by nearly 8%. But the negativity was short-lived, as investors continue to see downside moves as just more reason to pick up more shares.

All in all, AMZN seems headed toward more long-term success — it’s just hard to shake the haunting possibility that the next disappointing report is the straw that breaks the camel’s back and wakes investors up on the valuation front. Nonetheless, the chances of that happening seem slim enough that it’s not worth shorting Amazon, either.